• Partner With Us
  • Focus Areas
    • Cause Selection
    • Global Health & Wellbeing
      • Abundance & Growth
      • Effective Giving & Careers
      • Farm Animal Welfare
      • Global Aid Policy
      • Global Health & Development
      • Global Health R&D
      • Global Public Health Policy
      • Scientific Research
    • Global Catastrophic Risks
      • Biosecurity & Pandemic Preparedness
      • Forecasting
      • Global Catastrophic Risks Capacity Building
      • Potential Risks from Advanced AI
    • Other Areas
      • History of Philanthropy
  • Grants
  • Research & Updates
    • Blog Posts
    • In the News
    • Research Reports
    • Notable Lessons
  • About Us
    • Grantmaking Process
    • How to Apply for Funding
    • Careers
    • Team
    • Operating Values
    • Stay Updated
    • Contact Us
  • Partner With Us
  • Focus Areas
    • Cause Selection
    • Global Health & Wellbeing
      • Abundance & Growth
      • Effective Giving & Careers
      • Farm Animal Welfare
      • Global Aid Policy
      • Global Health & Development
      • Global Health R&D
      • Global Public Health Policy
      • Scientific Research
    • Global Catastrophic Risks
      • Biosecurity & Pandemic Preparedness
      • Forecasting
      • Global Catastrophic Risks Capacity Building
      • Potential Risks from Advanced AI
    • Other Areas
      • History of Philanthropy
  • Grants
  • Research & Updates
    • Blog Posts
    • In the News
    • Research Reports
    • Notable Lessons
  • About Us
    • Grantmaking Process
    • How to Apply for Funding
    • Careers
    • Team
    • Operating Values
    • Stay Updated
    • Contact Us

Evidence for Common Oral Hygiene Practices

  • Content Type: Research Reports

Table of contents

1 My process

2 My findings

2.1 Topical fluorides (e.g. toothpaste)
2.2 Flossing
2.3 Water fluoridation
2.4 Summary of findings

3 Sources

Published: April 01, 2016

As part of the Open Philanthropy Project’s efforts to understand cross-cutting issues in the social and health sciences, I (Luke Muehlhauser) conducted a rapid review1 of the evidence supporting some common oral hygiene practices.

My overall tentative conclusion is that there appears to be good evidence that topical fluorides (e.g. various toothpastes) prevent tooth decay, but there is not good evidence that flossing or water fluoridation is beneficial to oral health. There is very little in the way of evidence regarding flossing, even though it seems to me that high-quality randomized studies on this topic would be practical.

1 My process

I spent less than one hour on this rapid review.

Given this limitation, I looked only for systematic reviews released by the Cochrane Collaboration2 (hereafter, “Cochrane”), a good source of reliably high-quality systematic reviews of intervention effectiveness evidence. I also conducted a few Google Scholar keyword searches to see whether I could find compelling articles challenging the Cochrane reviews’ conclusions, but I did not quickly find any such articles.

I looked only for evidence concerning the health benefits of three common oral hygiene practices: topical fluorides (e.g. toothpaste), flossing, and water fluoridation.

2 My findings

2.1 Topical fluorides (e.g. toothpaste)

On the effectiveness of topical fluorides, a 2003 Cochrane review3 concluded:

The review of [randomized or quasi-randomized] trials found that children aged 5 to 16 years who applied fluoride in the form of toothpastes, mouthrinses, gels or varnishes had fewer decayed, missing and filled teeth regardless of whether their drinking water was fluoridated. Supervised use of self applied fluoride increases the benefit. Fluoride varnishes may have a greater effect but more high quality research is needed to be sure of how big a difference these treatments make, and whether they have adverse effects.

Over the next decade, more evidence concerning fluoride varnishes accumulated, and a 2013 Cochrane review4 concluded:

The evidence produced has been found to be of moderate quality due to issues with trial designs. However in the 13 trials that looked at children and adolescents with permanent teeth the review found that the young people treated with fluoride varnish experienced on average a 43% reduction in decayed, missing and filled tooth surfaces. In the 10 trials looking at the effect of fluoride varnish on first or baby teeth the evidence suggests a 37% reduction in decayed, missing and filled tooth surfaces. There was little information concerning possible adverse effects or acceptability of treatment.

A 2010 Cochrane review5 specific to fluoride toothpaste also concluded:

This review includes 79 [randomized] trials on 73,000 children. As expected the use of toothpaste containing more fluoride is generally associated with less decay. Toothpastes containing at least 1000 parts per million (ppm) fluoride are effective at preventing tooth decay in children, which supports the current international standard level recommended.

2.2 Flossing

A 2011 Cochrane review6 concluded:

Twelve trials were included in this review which reported data on two outcomes (dental plaque and gum disease). Trials were of poor quality and conclusions must be viewed as unreliable. The review showed that people who brush and floss regularly have less gum bleeding compared to toothbrushing alone. There was weak, very unreliable evidence of a possible small reduction in plaque. There was no information on other measurements such as tooth decay because the trials were not long enough and detecting early stage decay between teeth is difficult.

2.3 Water fluoridation

A 2015 Cochrane review7 concluded:

There is very little contemporary evidence, meeting the review’s inclusion criteria, that has evaluated the effectiveness of water fluoridation for the prevention of caries.

The available data come predominantly from studies conducted prior to 1975, and indicate that water fluoridation is effective at reducing caries levels in both deciduous and permanent dentition in children. Our confidence in the size of the effect estimates is limited by the observational nature of the study designs, the high risk of bias within the studies and, importantly, the applicability of the evidence to current lifestyles. The decision to implement a water fluoridation programme relies upon an understanding of the population’s oral health behaviour (e.g. use of fluoride toothpaste), the availability and uptake of other caries prevention strategies, their diet and consumption of tap water and the movement/migration of the population. There is insufficient evidence to determine whether water fluoridation results in a change in disparities in caries levels across [socioeconomic status]. We did not identify any evidence, meeting the review’s inclusion criteria, to determine the effectiveness of water fluoridation for preventing caries in adults.

2.4 Summary of findings

In short, the relevant Cochrane reviews suggest that:

There is good evidence that topical fluorides (e.g. toothpaste) prevent tooth decay, at least in children in adolescents. I don’t know of a reason to expect adult teeth to respond differently, but I haven’t tried to find such reasons.

There is not good evidence in favor of flossing for preventing tooth decay or gum disease.

There is not good evidence supporting the effectiveness of water fluoridation for preventing dental caries.

There is very little in the way of evidence regarding flossing, even though it seems to me that high-quality randomized studies on this topic would be practical.

3 Sources

DOCUMENT SOURCE
Cochrane Collaboration Source (archive)
Harker & Kleijnen (2012) Source (archive)
Iheozor-Ejiofor et al. (2015) Source (archive)
Marinho et al. (2003) Source (archive)
Marinho et al. (2013) Source (archive)
Sambunjak et al. (2011) Source (archive)
Walsh et al. (2010) Source (archive)
Expand Footnotes Collapse Footnotes

1.For more on the concept of rapid reviews, see Harker & Kleijnen (2012).

2. Cochrane Collaboration

3. Marinho et al. (2003)

4. Marinho et al. (2013)

5. Walsh et al. (2010)

6. Sambunjak et al. (2011)

7. Iheozor-Ejiofor et al. (2015)

Subscribe to new blog alerts
Open Philanthropy
Open Philanthropy
  • We’re Hiring!
  • Press Kit
  • Governance
  • Privacy Policy
  • Stay Updated
Mailing Address
Open Philanthropy
182 Howard Street #225
San Francisco, CA 94105
Email
info@openphilanthropy.org
Media Inquiries
media@openphilanthropy.org
Anonymous Feedback
Feedback Form

© Open Philanthropy 2025 Except where otherwise noted, this work is licensed under a Creative Commons Attribution-Noncommercial 4.0 International License.

We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept All”, you consent to the use of ALL the cookies. However, you may visit "Cookie Settings" to provide a controlled consent.
Cookie SettingsAccept All
Manage consent

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary
Always Enabled
Necessary cookies are absolutely essential for the website to function properly. These cookies ensure basic functionalities and security features of the website, anonymously.
CookieDurationDescription
cookielawinfo-checkbox-analytics11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics".
cookielawinfo-checkbox-functional11 monthsThe cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional".
cookielawinfo-checkbox-necessary11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary".
cookielawinfo-checkbox-others11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.
cookielawinfo-checkbox-performance11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".
viewed_cookie_policy11 monthsThe cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. It does not store any personal data.
Functional
Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features.
Performance
Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors.
Analytics
Analytical cookies are used to understand how visitors interact with the website. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc.
Advertisement
Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. These cookies track visitors across websites and collect information to provide customized ads.
Others
Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet.
SAVE & ACCEPT